This anime lays it's best qualities in it's characters. It's kind of like filling a grey, boring room with clowns talking about whatever you like talking about most. In other words, while the story doesn't progress much and there is filler everywhere you look, the characters are colorful and interesting beyond any other anime I have ever watched. Almost every character has an odd, sometimes physics defying hair do that just screams originality and creativity. They will also have some kind of tic, or defining characteristic that makes them not only interesting, but lovable. That being said, they can also be very annoying so it's a coin flip on which characters you'll enjoy. But I always want to get to the next arc to see what Oda has created next.
The story is made so that they can strech the series as long as needed which means there is the main plot that never gets farther than "We are getting slightly closer but there are so many places we haven't goofed off on yet." So you kind of have to live arc by arc. The stories inside the arcs aren't very different either. Some bad guy is ruining an island and is entirely too powerful for anyone to fight back, then the Strawhat crew arrives and wether it be because the bad guy has something they need, they want to help, or just want to get the hell off the island, they stand by while Luffy uses his powers to completely destroy said bad guy. Then he gets magically healed up in a short amount of time and does it all again.
The sounds are slighly better than average, but enjoyable nonetheless. The animation works very well with this anime and I found myself enjoying it. It makes the characters look extremely odd but it just makes them better. Although it's sometimes frustrating because from the view point the sizes of people and things change a lot.
Overall this is one of the most creative animes I've ever seen and my favorite by far. There are so many characters that you will definatly have trouble putting a favorite list together. Sorry if I missed anything or said something stupid, but this is my first review so please be gentle :)